Thin Film Transistor-Liquid Crystal Display (TFT-LCD) plays a leading role in the current market for flat panel displays due to its advantages of small size, light weight, low power consumption, irradiation-free, etc. A display panel of the TFT-LCD is formed in such a way that an array substrate and a counter substrate (e.g. a color filter substrate) are bonded together, and a gap between them is vacuumized and then a liquid crystal material is injected into it and sealed. On the display panel of the TFT-LCD, a pixel structure array constituted by hundreds of thousands to a million of pixel structures is formed, and these pixel structures act to display images under the control of TFTs.
At present, ADS has been widely used due to its advantage of wide viewing angle. ADS is the abbreviated form of ADSDS (ADvanced Super Dimension Switch), i.e. an Advanced Super Dimension Switch technology, in which a multi-dimensional electric field is formed by an electric field created at edges of strip-like electrodes in the same plane and an electric field created between a layer with strip-like electrodes and a plate-like electrode layer, so as to allow all the liquid crystal molecules with different orientations in a liquid crystal cell, which are located directly above the electrode and between the strip-like electrodes, to be rotated, thereby enhancing the work efficiency of liquid crystals and increasing the transmission efficiency. The Advanced Super Dimensional Switch technology is capable of improving the image quality of TFT-LCD products, and has advantages of high resolution, high transmittance, low power consumption, wide viewing angle, high aperture ratio, low chromatic aberration, push Mura-free, etc.
Generally, a pixel structure of an ADS mode TFT-LCD contains a plurality of sub-pixel structures. The configuration of an existing sub-pixel structure on an array substrate is shown in FIG. 1 and it comprises: a gate line 10 and a data line 20 perpendicular to each other, a thin film transistor 30 located in an intersection region of the gate line 10 and the data line 20, a sub-pixel electrode 40 (i.e. the plate-like electrode), and common electrodes 50 (i.e. a plurality of strip-like electrodes) formed in a region surrounded by the gate line 10 and the data line 20. The thin film transistor 30 is located above the gate line, wherein the gate electrode of the thin film transistor 30 is connected to the gate line 10, the drain electrode of the thin film transistor 30 is connected to the data line 20, and the source electrode of the thin film transistor 30 is connected to the sub-pixel electrode 40. The sub-pixel electrode 40 and the common electrodes 50 overlap with each other. Liquid crystal electric fields created between the common electrodes 50 and the sub-pixel electrode 40 is a multi-dimensional electric field and has a uniform direction. All the common electrodes 50 in this sub-pixel structure have a uniform direction, namely, a one-domain structure. In this structure, due to the uniform direction of multi-dimensional liquid crystal electric fields created between the common electrodes 50 and the sub-pixel electrode 40, liquid crystal molecules in one sub-pixel structure are tilted in a uniform deflection direction, thus resulting in a color deviation.
In order to solve the above problem of color deviation, a double-domain structure is used for sub-pixel structures of ADS mode TFT-LCDs currently. The configuration of a double-domain sub-pixel structure, on an array substrate, of an existing ADS mode TFT-LCD is shown in FIG. 2. As shown in FIG. 2, a sub-pixel structure of the ADS mode TFT-LCD comprises a gate line 10, a data line 20, a thin film transistor 30, a sub-pixel electrode 40 and common electrodes 50 on the array substrate. Different from the common electrodes 50 in the one-domain sub-pixel structure, the common electrodes 60 of the double-domain sub-pixel structure contain two kinds of strip-like common electrodes 61 and 62 which have different orientations. The direction of a liquid crystal electric field in a first domain created between the strip-like common electrodes 61 and the sub-pixel electrode 40 is different from the direction of a liquid crystal electric field in a second domain created between the strip-like electrodes 62 and the sub-pixel electrode 40. Because the liquid crystal electric fields created between the common electrodes 60 and the sub-pixel electrode 40 are classified into two domains, liquid crystal molecules can be tilted in two different directions. Thus, the problem of color deviation can be improved effectively.
However, since the liquid crystals at the interface of the two domains are non-uniformly tilted, a dark region is generated in a display area of the display panel.
As can be seen, in the existing ADS mode TFT-LCD which has the two-domain sub-pixel structure, the dark region is likely to occur, and the image quality of the liquid crystal display is not very satisfactory.